Missing state properties and negation operator behave differently client/server

[jonsurrell]

With a directive like the following:

<div data-wp-bind--hidden="!state.missing.property">
	This should be hidden by the <code>hidden</code> attribute.
</div>

The server will render the following HTML:

<div data-wp-bind--hidden="!state.missing.property">
	This should be hidden by the <code>hidden</code> attribute.
</div>

But the client will immediately set the hidden attribute (the expected behavior):

<div data-wp-bind--hidden="!state.missing.property" hidden="">
	This should be hidden by the <code>hidden</code> attribute.
</div>

The client and server should align on the behavior of the negation operator with directives to missing paths.

Trac ticket: https://core.trac.wordpress.org/ticket/62374

With a directive like the following:

This should be hidden by the hidden attribute.

The server will render the following HTML:

This should be hidden by the hidden attribute.

But the client will immediately set the hidden attribute (the expected behavior):

This should be hidden by the hidden attribute.

The client and server should align on the behavior of the negation operator with directives to missing paths.

---

​The client side implementation allows negation to happen when state is missing.

The server side implementation skipped a possible negation when state is missing.

[cbravobernal]

In 59398:

Interactivity API: Allow missing state negation on server

Aligns on the behavior of the negation operator with directives to missing paths in client and in server.

With a directive like the following:

<div data-wp-bind--hidden="!state.missing.property">
	This should be hidden by the <code>hidden</code> attribute.
</div>

Both server and client will return with this fix:

<div data-wp-bind--hidden="!state.missing.property" hidden="">
	This should be hidden by the <code>hidden</code> attribute.
</div>

Props jonsurrell, luisherranz.
Fixes #62374.

Commited with https://core.trac.wordpress.org/changeset/59398

[cbravobernal]

Reporting for 2nd committer review and sign-off for backporting https://core.trac.wordpress.org/changeset/59398 to the 6.7 branch.

[cbravobernal]

In 59404:

Interactivity API: Allow missing state negation on server

Aligns on the behavior of the negation operator with directives to missing paths in client and in server.

With a directive like the following:

<div data-wp-bind--hidden="!state.missing.property">
	This should be hidden by the <code>hidden</code> attribute.
</div>

Both server and client will return with this fix:

<div data-wp-bind--hidden="!state.missing.property" hidden="">
	This should be hidden by the <code>hidden</code> attribute.
</div>

Reviewed by cbravobernal.
Merges [59398] to the 6.7 branch.

Props jonsurrell, luisherranz.
Fixes #62374.

Backported to 6.7 with https://core.trac.wordpress.org/changeset/59404